Vendored dependancies using go mod (cloudflare#246)

* Vendored dependancys using `go mod`

* Adjust .travis.yml to use vendor correctly

Using info from https://arslan.io/2018/08/26/using-go-modules-with-vendor-support-on-travis-ci/ .

.travis.yml

@@ -1,14 +1,28 @@
 language: go
 sudo: false
+
+env:
+  global:
+    - MOD_VENDOR=""
+
 matrix:
   fast_finish: true
   include:
     - go: 1.9.x
     - go: 1.10.x
     - go: 1.11.x
+      env:
+        - GO111MODULE=on
+        - MOD_VENDOR="-mod=vendor"
     - go: 1.x
-      env: LATEST=true
+      env:
+        - LATEST=true
+        - GO111MODULE=on
+        - MOD_VENDOR="-mod=vendor"
     - go: tip
+      env:
+        - GO111MODULE=on
+        - MOD_VENDOR="-mod=vendor"
   allow_failures:
     - go: tip
 
@@ -20,10 +34,10 @@ install:
   - # skip
 
 script:
-  - go get -t -v ./...
+  - if [ "$GO111MODULE" != "on" ]; then go get -t -v ./... ; else true; fi
   - golint -set_exit_status . cmd/flarectl
-  - go vet $(go list ./... | grep -v /vendor/)
-  - go test -v -race ./...
+  - go vet $MOD_VENDOR $(go list $MOD_VENDOR ./... | grep -v /vendor/)
+  - go test -v -race $MOD_VENDOR ./...
   # Only build binaries from the latest Go release.
   - if [ "${LATEST}" = "true" ]; then gox -os="linux darwin windows" -arch="amd64" -output="flarectl.{{.OS}}.{{.Arch}}" -ldflags "-X main.Rev=`git rev-parse --short HEAD`" -verbose ./...; fi
 

go.mod

@@ -0,0 +1,13 @@
+module github.com/cloudflare/cloudflare-go
+
+require (
+	github.com/codegangsta/cli v1.20.0
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/mattn/go-runewidth v0.0.3 // indirect
+	github.com/olekukonko/tablewriter v0.0.1
+	github.com/pkg/errors v0.8.0
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2
+	golang.org/x/net v0.0.0-20181029044818-c44066c5c816 // indirect
+	golang.org/x/time v0.0.0-20180412165947-fbb02b2291d2
+)